Birdsong is a novel about the destructive nature of warfare, and how World War I affected soldiers and civilians psychologically, emotionally and physically. This historical novel chronicles a dark time in history, when humanity was experiencing an unprecedented number of deaths in combat, due to the large scale of World War I. Focusing on the experience of soldiers during the war, Faulks offers an insight into the horrors of trench warfare, and the impact these unimaginable experiences had on soldiers for the rest of their lives. He writes, "they had seen things no human eyes had looked on before, and they had not turned their gaze away," which emphasizes the unprecedented experience of warfare at the beginning of the 20th Century, due to technological advancements in the military. This experience is something that many writers at the time attempted to convey, including war poets Wilfred Owen and Siegfried Sassoon. Through his character Elizabeth, Faulks shows the importance of trying to understand the experience of World War I in the modern age.
The novel also emphasizes the importance of literature, including personal journals and poetry, in understanding the experience of warfare. This is because many of the soldiers failed to express their feelings, due to concerns about perceived masculinity, and also an inability to put their experience into words: "No child or future generation will ever know what this was like. They will never understand. When it is over we will go quietly among the living, and we will not tell them. We will seal what we have seen in the silence of our hearts and no words will reach us." As such, literature is incredibly important in providing an insight into this experience, which otherwise might not have been understood fully. This is represented by the fact Elizabeth finds her grandfather's journal and understands more about his feelings and experiences by reading it.
Although often cited as a war novel, Birdsong is also an incredible love story. The text begins with a passionate affair between Isabelle and Stephen, which largely takes place in the symbolic red room. This love affair is something that stays with Stephen throughout his life, and even into his marriage later in the text. As such, this love story shows how intense love and passion can exist at the same time as a destructive war. In a similar sense, Faulks also shows how nature prevails and continues despite human disasters and misery. On the battlefield, the sound of birdsong can be heard, which represents the perseverance of nature and a sense of hope and optimism for the future. As such, this text shifts between the darker side of humanity and a more hopeful view.
